The present invention relates to the field of ordnance firing mechanisms for striking detonators.
In known manner, ordnance firing mechanisms comprise a spring-driven strike pin which is compressed, and forces the strike pin into an armed, retracted position during the entire time of weapon use, that is, as long as firing has not been triggered. When the strike pin is released, the spring projects onto the detonator""s primer to ensure ignition. It follows that such a firing mechanism will require means for releasing the strike pin and means for restoring it to its initial position and locking it. A strike pin of this kind is described in U.S. Pat. No. 2,245,621, the pin being reset into its armed position as the breech is being closed. Such a system is undesirable because it might lead to premature firing and put weapon operators in great danger.
German Patent 147,526 describes an ordnance firing mechanism or igniter comprising a spring-driven strike pin. A latch stop permits retraction of the strike pin by extending its spring when rotating a weapon lever. This lever in turn rotates a second lever about a shaft comprising a pawl cooperating with the latch. At the end of the rotation of the weapon""s lever, the pawl detaches from the latch and thereby releases the strike pin.
This design allows extending the strike-pin spring only at the time of firing, whereby the previously cited drawbacks are avoided. Nevertheless this design entails rotating the weapon lever which in turn provides a substantial clearance volume underneath the firing mechanism.
An objective of the present invention is to provide a novel design for operating a strike pin, whereby a spring attached to said strike pin need not be subjected to constant tension and bulk is substantially reduced.
Accordingly an objective of the invention is an ordnance firing mechanism operating by striking a detonator with a strike pin translationally displaceable relative to a support, said strike pin being translationally driven by actuation systems consecutively assuring that:
the strike pin will move from a rest position into an armed position wherein a propelling device for the strike pin is armed;
the strike pin will be moved from the armed position to a firing position wherein it is propelled by the propelling device onto a detonator; and
the strike pin will be kept in said rest position, the actuation systems ensuring that the strike pin will be kept in said rest position.
The firing mechanism or igniter is characterized in that the actuation systems comprise:
a lever connected to the strike pin and pivoting relative to the support;
a pivoting pawl which can release the lever;
a propelling device driving the lever and firmly joined to the support; and
drive means acting on the pawl and through it causing the lever to rotate and then arm the strike pin, and then release the strike pin.
The drive means setting the lever in rotation comprises a control rod which is translationally displaceable relative to the support, the rod being fitted with recesses cooperating with the pawl on one hand and on the other with a heel cooperating with the lever.
Advantageously a first recess comprises a cylindrical contour wherein the pawl begins its rotation, followed by a second recess wherein the pawl will be masked to allow the lever to rotate about its shaft.
The depth of the second recess corresponds to the strike path of the strike pin.
Advantageously the heel is situated beyond the second recess to cooperate with a slope on the lever to return this lever to its initial position.
The rod is restored to its initial position by a return spring and it is driven in rotation by a hydraulic piston or jack.
The lever""s propelling device is an arm, one end of which rests against the lever and the other end of which is rigidly joined to a torsion bar, the other arm end and the torsion bar being affixed to the support.
One end of the lever is affixed to the strike pin and the other end to a shaft rotating relative to the support, the pawl being mounted in rotatable manner about this lever at a location between its two ends.
The torsion bar is initially prestressed.
The lever may be in the form of a plate comprising clearances to reduce its moment of inertia.
Advantageously the pawl is attached by a spring to the lever.
In a particular embodiment of the invention, the strike pin comprises a first groove perpendicular to the strike-pin""s axis and entered by the end of the lever, and a stud projecting from said groove keeps the lever in it.
The strike pin is fitted with means permitting its removal and comprising at lest two recesses on the rear side to permit gripping it, and a second groove parallel to the strike-pin axis and communicating with the first groove, the lever moving through the second groove following retraction of the stud and rotation of the strike pin.
A first feature of the apparatus of the invention is that the strike pin always is in the rest position when the weapon""s breech is closed.
Another feature of the invention is that the strike pin is not kept in place by a stop means precluding spring relaxation.
Another advantage of the invention is the ability to adjust the prestressing of the torsion bar.
Another advantage is igniter compactness.